syzbot


KASAN: use-after-free Read in reiserfs_read_locked_inode

Status: fixed on 2021/01/15 04:02
Reported-by: syzbot+dfe6b98208f4b9044e1f@syzkaller.appspotmail.com
Fix commit: b8590c82b3cc reiserfs: add check for an invalid ih_entry_count
First crash: 646d, last: 564d

Fix bisection: fixed by (bisect log) :
commit b8590c82b3ccf9fb4d9f0b0b097be10736869333
Author: Rustam Kovhaev <rkovhaev@gmail.com>
Date: Sun Nov 1 14:09:58 2020 +0000

  reiserfs: add check for an invalid ih_entry_count

similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Read in reiserfs_read_locked_inode C done 5 545d 649d 1/1 fixed on 2021/02/20 09:47

Sample crash report:
reiserfs: using flush barriers
REISERFS (device loop0): journal params: device loop0, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
==================================================================
BUG: KASAN: use-after-free in init_inode fs/reiserfs/inode.c:1327 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x216f/0x2220 fs/reiserfs/inode.c:1580
Read of size 4 at addr ffff88807c172000 by task syz-executor614/6500

CPU: 1 PID: 6500 Comm: syz-executor614 Not tainted 4.19.150-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x22c/0x33e lib/dump_stack.c:118
 print_address_description.cold+0x56/0x25c mm/kasan/report.c:256
 kasan_report_error.cold+0x66/0xb9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load_n_noabort+0x8b/0xa0 mm/kasan/report.c:443
 init_inode fs/reiserfs/inode.c:1327 [inline]
 reiserfs_read_locked_inode+0x216f/0x2220 fs/reiserfs/inode.c:1580
 reiserfs_fill_super+0x172e/0x2e60 fs/reiserfs/super.c:2084
 mount_bdev+0x2fc/0x3b0 fs/super.c:1158
 mount_fs+0xa3/0x318 fs/super.c:1261
 vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 do_new_mount fs/namespace.c:2469 [inline]
 do_mount+0x51c/0x2f10 fs/namespace.c:2799
 ksys_mount+0xcf/0x130 fs/namespace.c:3015
 __do_sys_mount fs/namespace.c:3029 [inline]
 __se_sys_mount fs/namespace.c:3026 [inline]
 __x64_sys_mount+0xba/0x150 fs/namespace.c:3026
 do_syscall_64+0xf9/0x670 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447d7a
Code: b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 7d a3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 5a a3 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffc7fd77f28 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc7fd77f80 RCX: 0000000000447d7a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffc7fd77f40
RBP: 00007ffc7fd77f40 R08: 00007ffc7fd77f80 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000006
R13: 0000000000000004 R14: 0000000000000003 R15: 0000000000000003

The buggy address belongs to the page:
page:ffffea0001f05c80 count:0 mapcount:0 mapping:0000000000000000 index:0x1
flags: 0xfffe0000000000()
raw: 00fffe0000000000 ffffea0001f05cc8 ffff8880ae32fc88 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88807c171f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807c171f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807c172000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88807c172080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807c172100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-19 2020/10/16 22:52 linux-4.19.y a1b977b49b66 6e262c73 .config log report syz C
ci2-linux-4-19 2020/10/06 21:20 linux-4.19.y b09c34517e1a 1880b4a9 .config log report syz C
ci2-linux-4-19 2020/09/24 19:47 linux-4.19.y d09b80172c22 54289b08 .config log report syz C
ci2-linux-4-19 2020/09/24 19:00 linux-4.19.y d09b80172c22 54289b08 .config log report info